Testing and modelling of micro cement paste cube under indentation splitting

Cement paste is the glue that holds concrete together and any improvements in material performance will come from its microstructure. For better understanding and predicting its elastic properties and fracture performance, more and more studies are carried out based on micromechanics simulations. However, the predicted results can be hardly verified experimentally due to the technical limitations. This paper presents a procedure for validating micromechanics simulation by making, testing and modelling deformation and fracture of micro cement paste cube (100 mu m x 100 mu m x 100 mu m). The micro scale specimens were produced by a micro dicing saw which is commonly employed in the semiconductor industry and fractured by a commercial cylindrical wedge tip mounted on a nano-indenter equipment. A combination of X-ray computed tomography technique and a discrete lattice fracture model was applied to simulate the deformation and fracture performance of the micro scale specimen under indentation. Mechanical properties of local phases are the input for this fracture simulation, which are taken from the previous study by the authors, wherein a micro scale experiment is developed to calibrate these values. Load-displacement curve and crack pattern from the simulation show a good agreement with those obtained experimentally. The proposed technique forms the basis for experimental validation of simulation tools that are used in a multi-scale framework at every scale.